Charge forming device



June 15, 1954 o. J. EICKMANN CHARGE FORMING DEVICE 5 Sheets-Sheet 1Filed Oct. 2. 1950 FIG.|.

INVENTOR. OLIN J. EICKMANN 7/F ATTORNEY June 15, 1954 o. J. EICKMANN2,681,214

CHARGE FORMING DEVICE Filed Oct. 2, 1950 5 Sheets-Sheet 2 22 FIGS.

- INVENTOR. OLIN J. EICKMANN ATTORNEY June 15, 1954 J, ElcKMANN2,681,214

CHARGE FORMING DEVICE Filed Oct. 2, 1950 5 Sheets-Sheet 5 H I! I I (11Ill} INVENTOR. OL-IN J. EICKMANN ATTORNEY June 15, 1954 J, E|KMANN2,681,214

CHARGE FORMING DEVICE Filed 001:. 2, 1950 5 Sheets-Sheet 4 INVENTOR.FIG. 7. OLIN J.EICKMANN ATTORNEY June 15, 1954 o. J. EICKMANN 2,681,214

CHARGE FORMING DEVICE Filed 001:. 2, 1950 5 Sheets-Sheet 5 INVENTOR. FIG. 8. OLIN J. EICKMANN ATTORNEY Patented June 15, 1954 UNITED STATEATENT OFFICE CHARGE FORMING DEVICE Application October 2, 1950, SerialNo. 187,887

29 Claims. 1

This invention relates to fuel mixing devices for internal combustionengines of the spray carburetor type, and particularly to suchcarburetors which may be required to handle gasolines which may containa large proportion of low temperature boiling constituents.

The increasing use of highly volatile fuels has presented seriousproblems on account of the tendency of the fuel to boil and cause vaporlock and disturbance of the mixture ratios when the temperatures arehigh, and also to cause icing at lower temperatures.

Another serious problem presented by carburetors of previous design hasbeen their inability to produce homogeneous mixtures and evendistribution, particularly during variation of throttle position andchanges in engine speeds.

Some previous attempts to avoid icing and poor fuel distribution byplacing the throttle anterior to the fuel nozzle have been made, butthese attempts have not been successful, chiefly by reason of thetendency to cause violent boiling of the fuel in the float chamber andnozzles whenever the throttle is closed.

Certain subject matter shown in this application is claimed in mycopending application Serial No. 164,544, filed May 26, 1950, forCarburetor and Method of Carburetion, now abandoned.

It is an object of my invention to produce a new and generally improvedform of carburetor,

in which the throttle is placed anterior to the fuel nozzle so as toobtain the advantages of the anterior throttle design withoutencountering the disadvantages caused by placing the fuel supply chamberand fuel nozzles under manifold suction when the throttle is in closedor idling position. It is a further object of this invention to producea carburetor of the above described character in which the richness ofthe fuel mixture is controlled in accordance with temperature during thestarting and warm-up period.

The problem of forming homogeneous fuel mixtures having the correctair-fuel ratio is sharply accentuated when the throttle is moved fromclosed to open position, or vice-versa. It is Well known that the enginerequires a much richer mixture from the carburetor when the throttle isin its idling position than when the throttle is open. This is partlybecause the volume of fresh mixture to be delivered to the engine isincreased, the proportion of fresh mixture to burnt gas is increased andtherefore the richness of the fresh mixture must be correspondinglyreduced. In conventional plain tube carburetor practice, this reductionof richness has been accomplished by having the idle port in the wall ofthe carburetor adjacent one edge of the butterfiy throttle valve so thatthe action of the port is varied during the opening movement of thethrottle. With a construction of this type, the idle port ceases todischarge fuel when the throttle is about or /2 way open and the fueldischarge function is then taken over by the main nozzle whichdischarges into the center of the mixing conduit at a point anterior tothe throttle and usually near the throat of a venturi.

Carburetors of the type just described are in almost universal use forautomobile engines, at present, but they present the seriousdisadvantage of being very hard to control at the point where thefunction of fuel supply is transferred from the idle port to the mainnozzle, or vice-versa. Carburetor engineers have probably spent moretime in attempts to cover up the transfer point than in any other phaseof carburetion.

It is an object of this invention to provide a new and improved plaintube carburetor in which there is no transfer point and in which thefunction of discharging fuel is customarily performed from idling towide open throttle by a single fuel supply system.

Another object is to provide novel means and method for supplying atemporary increase in the supply of fuel to the engine intake duringacceleration.

These objects and other more detailed objects hereafter appearing areattained by the structure illustrated in the accompanying drawings inwhich:

Figure 1 is an elevation showing the novel carburetor mounted on anengine manifold.

Figure 2 is a top view of the carburetor considerably enlarged.

Figure 3 is a vertical section on line 3-3 of Figure 2.

Figure 4 is a horizontal section on line 4-4 of Figure 3. I

Figure 5 is a horizontal section on line 5- 5 of Figure 3.

Figure 6 is an enlarged fragmentary view of the ports adjacent thethrottle valve.

Figure 7 is a section similar to Figure 3, but showing a modification,like parts, in most cases, having the same reference numerals with theletter a added.

Figure 8 is a section similar to Figures 3 and 4, but showing anothermodification, like parts, in

3 most cases, having the same reference numerals with the letter 1)added.

Figure 1 shows the carburetor, generally indicated at it, attached tothe hot spot portion H of an engine manifold system including the intakemanifold, shown in part at E2, and the exhaust manifold at i 3. Thecarburetor has a housing id enclosing a thermostatic control to bedescribed hereafter and connected by a tube to a stove IE mounted on theexhaust manifold for supplying hot air.

The carburetor comprises a downdraft mixture conduit including an upperair inlet portion 13, which may be arranged for mounting of an aircleaner, a series of Venturi tubes is and a discharge portion Zfiflanged as at 2! for attachment to the manifold. Adjacent the mixtureconduit is a bowl 22, having a threaded boss 23 for connection to asource of fuel. within. which fuel is maintained at a substantiallyconstant level by a float 2d and the usual needle valve mechanism (notshown). A main fuel passage 25' extends from the lower part of the fuelbowl upwardly at an angle and discharges through amain fuel nozzle 22:into smallest Venturi tube IS. A. metering restriction for the main fuelsupply is shown at 2'3.

A butterfly throttle valve 29 is mounted in the air inletportion of thecarburetor on a shaft which rigidly mounts a manual operating lever 3!outside the carburetor. Lever 34 carries an idle speed adjusting screw32' which cooperates with a stop 33 on the carburetor mixture barrel.

The fuel bowl is sealed from the atmosphere,

except through a bowl pressure control duct 35 leading transversely fromthe top of the bowl to a vertical passage 35 on the opposite side of themixturev conduit. Passage 35, at its lower end, has a restriction 38 andopens into the mixture conduit through a cross port 36 controlled by aplug or drum type enriching valve 3? to be described hereafter. At itsupper end, passage 35 connects with the mixture conduit anterior tothrottle .29 through an upwardly inclined cross tube 39 containing arestriction controlled by a .1

needle valve ll. The mouth of cross tube 39 is cut at an angle of aboutto the vertical so as to face against the direction of air flow in themixture conduit. The upward inclination of tube 32 tends to preventcollection of condensed vapors therein.

A main air bleed duct consisting of passages 42 and M, containingrestriction 35, leads from .main fuel passage 25 to tube 36 locatedanterior to the throttle valve. Passage d2 is in communication with airinlet portion lt through port 33 located immediately anterior tothrottle valve 29. when the throttle valve is in closed position. Theposition of this port is such that it is swept by. the edge of thethrottle valve during the early part of the throttle opening movementfrom dead idle and thereafter part or all of port as is exposed toengine suction for the purpose of reducing the value of the air bleed tonozzle 25 which in turn increases fuel discharge from said nozzle. Themain air bleed passage also communicates with the main nozzle passagethrough branch passage e! for calibrating purposes. This latter passageti, however, is optional. The intersections of bleed l2 and diagonalpassage 4'1 withmainfuel passage '25 are both normally below the normalfuel level and constitute metering points which may be proportioned asrequired. Inlet it of the carburetor will be at substantiallyatmospheric pressure during normal operation.

The angles of the open ends of tubes 1% and 39 are subject to variationsto adjust the mixture proportions required under various operatingconditions.

In order to further limit the bad effects of percolation, main nozzle28, above restriction 2?, is of ample diameter to permit breakage ofindependent bubbles from the surface of the fuel.

Drum valve 3? provides for adjusting: the pressure in bowl 22, andconsequently, enriching the fuel discharge during starting and warm-upand also provides for a fast idle. This valve extends into housing I l,previously mentioned, which has a cover I la with a central pin 59 towhich is secured the inner end of a coiled thermostatic spring 50'. Athreaded boss 5i provides for connection of heat tube I5 to thethermostat casing. The outer end of the thermostat is connected by aloop 5% to a finger 5'2 on the outer extremity of a lever rigid withdrum valve 31. The arrangement is such that at low temperatures,thermostat 5i! unwinds and rotates drum valve 3.! counterclockwise, asviewed from the left side ofv Figure 3. This valve has a V-shaped,peripheral slot 55, in line with vertical passage 35 forming part of thebowl pressure control system, and also has a port 5% spaced therefrom.Port 5t, during rotation of valve 3'5, moves along the edge of curved,inclined wall 51, for exposing more or less of the port to the interiorof the thermostat housing. Slot and port 53 both communicate with crosspassage 36 and the interior of the mixture conduit through the hollowinterior of the drum valve.

The arrangement of slot 55 and port 56 is such that at low temperatures,as shown in Figure 7 (in which the drum valve is identical) the communication between passages 35a and a (33 and 35 in Fig. 3) through slot55 is substantially restricted. The eifect of this is that the pressurein the top of the fuel bowl is higher than is the casewhen the bowlpressure control system opens to a greater extent through cross port 35ainto the mixture conduit. This results in increased discharge of fuelfor starting and warm-up. At such time, port 55 is substantially openedto the interior of the thermostat housing and stove it so that theincreased how of air from heat tube 15 through port 33:: provides fastidle operation. As the thermostat becomes warm, due to the flow ofheated air through tube l5, it winds upon itself to rotate drum valve 37clockwise. as viewed from the left side of Figure '7, progressivelycutting off communication between port 36a and the inside of thethermostat housing through port 56, while increasing the communicationbetween port 35a and the bowl pressure control system so as to, ineffect, reduce the pressure on the fuel in the constant level bowl.Figure 8 shows the starting valve in a warm-up position with port 56 andslot 551) each only partially opened, respectively, to the interior ofthe thermostat housing and to bowl pressure passage 3%. During thewarm-up, the communication between heat tube 55 and the mixture conduitgradually decreases so that the supplemental feed of warm air to themixture conduit and, consequently, the idle speed are gradually reduced.

After starting, the bowl pressure control system, including thethrottle, and tube 39 opening into the conduit anterior to the throttle,co operate with the air bleed system, including port 33, just anteriorto the edge of the throttle when closed, passages 4d and tube 36,somewhat farther anterior to the throttle, to provide a properly meteredand modulated fuel flow in accordance with all speed and loadconditions. The carburetor operates economically, yet has adequate powerunder severe testing conditions, even Without the usual acceleratingpump, stepup, and separate idling system. After starting valve 31 hasreached its normal position of Figure 3, fuel modulation is obtainedwithout any valve or other moving part, except the throttle valve,simply by control of pressures in the fuel bowl and in the air bleedsystem. At normal engine temperature, only slight communication is provided through port 56 between the mixture conduit and heat tube I5 toinsure maintenance of the starting valve 31 in normal running position,

The functioning of the carburetor under accoloration and load conditionsis novel and advantageous. In conven ional posterior throttlecarburetors, it has been necessary to supplement the fuel supply at suchtimes by the use of an accelerating pump and step-up devices. Since thepressure on top of the fuel in the constant level chamber in mycarburetor varies in accordance with the induction system pressureapplied to port 36, of course, as moderated by air tube 39, andrestriction 38, there will be a sharp increase of bowl pressure when thethrottle is opened or the load on the engine increased. Simultaneously,the amount of air bled through the nozzle via passage 42 and Al isgreatly reduced due to the reduction of the pressure dinerential betweenthe nozzle tip at is and tube 516. Those two factors cause a surge offuel through the main nozzle and consequent added enrichment. The addedenrichment continues until the induction pressure again drops to normalso that a step-up or economizer effect is obtained without the use of ametering valve or supplemental feed. It will be noted that as thethrottle valve is moved to nearly fully open position, the anterior edgeof the valve 29 approaches the mouth of the tube 46b, so that theincoming air stream is directed toward the mouth of the tube as by aVane, thus causing the air to enter the tube and increase the pressureabove the fuel in the bowl 22. By this means, the rate of flow of fuelfrom the bowl out of the nozzle 26 is increased when the throttle ismoved to fully open position. Also, to be considered a factor inacceleration is the fact that when the edge of the throttle passesbeyond port 43, the diluting elfect of air in the bleed passage isfurther reduced.

The positioning of the main nozzle posterior to the throttle insures theexposure of the fuel discharge to the maximum suction available in theinduction system while, at no time during engine operation, will therebe a failure of suction at this point. The result is that vaporizationis improved and a supply of fuel is maintained in the main nozzle at alltimes. In previous carburetors, particularly, of the interconnected idletype, there has been a time interval required in transferring the fuelfeed from the idle system to the main nozzle. This time delay is avoidedin my carburetor. Furthermore, the interference of the throttle with thefree and direct flow of fuel, as present in posterior throttlecarburetors, is also avoided.

The control of the pressure on the fuel in the bowl, plus the variableair bleed through the nozzle, in accordance with induction pressure, asabove described, has a further important advantage in that a rich orpower mixture may be obtained for any throttle position upon drop ofmanifold suction. This advantage, heretofore, has required a separatevacuum step-up device with resultant increased cost and liability tomisfunctioning. In my carburetor, an increase of pressure, or decreaseof suction, in the manifold, as when the engine is subjected toincreased load, is promptly transmitted to the body of gaseous fluid inthe top of the fuel bowl and to the nozzle bleed system. Theproportionate increase in bowl pressure under such condition is greaterthan the increase in pressure at the mouth of main nozzle 26 due, inpart, to the effect of primary Venturi tube l9 and the location ofsuction port 36 outside the,

Venturi stack. Also, there is less air bled through the nozzle. The netresult is a desirable enrichment of the fuel mixture without movement ofthe throttle valve This new method of providing for mixture variation inaccordance with the requirements of economy, power, acceleration, andstarting operation, particularly, with the use of a constant level bowland without valves and metering pins, pistons, diaphragms, springs,etc., is an important feature of the invention, accounting for improvedoperation and greater simplicity and economy.

l7he form in Figure 7 differs from that in Figure 3 in that the bowlpressure control systern. including vertical passage 35a opens into themixture conduit through a port 5! immediately posterior to the edge ofthe throttle valve when closed, and an upwardly inclined cross tube 39ccontaining a restriction controlled by eedle valve did. In this form, aspreviously explained, enriching valve 3"! is shown in its cold startingposition. In this construction, port Ell cooperates with port 43a toshape the inner end of the part throttle curve, that is the mixturedelivery as the throttle starts to open from dead idle.

The form in Figure 8 differs from the previous form in that the airbleed system opens into the mixture conduit only through tube 45?), port43a of Figure 7 being omitted. The bowl pressure control system is thesame as in Figure 7, including passage 3% and. 35b, port 59b, inclinedtube 391?, and needle valve Mb. The enriching valve 31, in this form, isshown in the warm-up position, with the bowl pressure control systempartially open to the mixture conduit through cross passage 36b andpartially open to the interior of the thermostat housing and heat tubel5. This latter connection insures the drawing of hot air past thethermostat from the stove.

The various bleed and pressure controlling passages, with theiraccompanying restrictions, may be modified as required to obtain thenecessary fuel mixture, as determined by well known test procedures. Forinstance, the angle of impact tube 35 and air bleed tube it may bevaried, as may the positioning and sizes of ports 43 and till. Theexclusive use of all modifications as come within the scope of theappended claims is contemplated.

I claim:

1. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage leading from said bowl anddischarging into said conduit posterior to said valve, and a bowlpressure control duct leading from the upper part of said constant levelbowl to said conduit posterior to said throttle said 7;pressure-controllduct having a branch to a point in: said conduitanterior to said throttle.

2. Ina carburetor, a'mixture conduit, a throttle valve therein, a fuelbowl, a main fuel nozzle connecting said bowl and said conduit posteriorto; said valve, and bowl pressure control passages extending,respectively, from a zone of substantially atmospheric pressure and fromsaid conduttposterior to said throttle valve to the upper portion ofsaid bowl for applying to the fuel in saidbowl the resultant ofpressures in said passages.

3. Ina carburetor, a mixture conduit, a thrott le valve therein, aconstant level fuel bowl adjacent said conduit, a main fuel nozzleextend ing'froin the lower part of said bowl into said conduit posteriorto said valve, and bowl pressure control passages extending,respectively, from a zone of substantially atmospheric pressure and fromsaid conduit posterior to said throttle valve to the upper portion ofsaid bowl for applying to the fuel in said bowl the resuitant ofpressures in said passages.

2. On a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage extending from said bowlto said conduit posterior to said throttle valve, a fuel control meanscomprising an air bleed duct extending from said fuel passage to a portin the wall of said conduit immediately anterior the edge of saidthrottle valve when closed, and bowl pressure control passage meansextending from the upper portion of said fuel bowl into said mixtureconduit on opposite sides of said throttle valve, when closed.

5. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage extending from said bowlto said conduit posterior to said throttle valve, and fuel controlmcanscomprising an air bleed duct extending from said fuel passage to saidmixture conduit anterior to said valve, a valve swept port in said duct,and bowl pressure control passage extending from the upper portion ofsaid fuel bowl into said mixture conduit on opposite sides of saidthrottle valve when closed.

6'. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage extending from said bowlto said conduit posterior to said throttle valve, and fuel control meansconsisting of an air bleed duct leading from said fuel passage below thenormal level of fuel therein to said mixture conduit anterior to saidthrottle valve, and a bowl pressure control passage extending from theupper part of said bowl and having branches opening into said conduit onopposite sides of said valve.

7. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage extending from said bowlto said conduit posterior to said throttle valve, and fuel control meansconsisting of bowl pressure control passages extending, respectively,from a zone of substantially atmospheric pressure and from said conduitposterior to said throttle valve to the upper portion of said bowl, andan air bleed duct leading from said main fuel passage to said mixtureconduit anterior to said throttle, with a branch passage extending fromsaid air bleed duct to a valve swept port in the wall of said mixtureconduit immediately anterior to the valve for controlling the fueldischarge from said passage.

8'. A carburetor as described in claim 6 in hating in said conduit onopposite sides which the bowlpressure control passage opening; into saidconduit anterior to said throttle facesagainst the air flow in saidconduit.

9. A carburetor asdescribed in claimfi further including an adjustingvalve in said control pas sage.

10. A carburetor as described in claim 6 in which the bowl pressurecontrol passage opening into said conduit anterior to said throttle has.

a plurality of connections with said conduit, and a manually adjustableneedle valve in one of said connections.

11. In a carburetor, a mixture conduit, a.

throttle valve therein, a constant level bowl, a

main fuel passage connecting said bowl and said conduit posterior tosaid throttle valve, a bowl pressure control duct extending from theupper part of said bowl tov said mixture conduit for controlling thefuel discharge from said passage and a thermo-responsive enriching valvein said duct functioning to increase the pressure therein and in saidbowl for increasing the fuel discharge during starting and warm-up.

12. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level bowl, a main fuel passage connecting said bowl and saidconduit posterior to said throttle valve, a bowlthe pressure in and thefuel discharge from saidbowl into said conduit.

A carburetor as described in claim 12 in which said enriching valveincludes portions for reducing the effective size of the connectionbetween said bowl pressure control duct and saidconduit, whileincreasing the effective size of the connection between said conduit andsaid zoneof atmospheric pressure.

1.4. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl,

a main fuel passage extending from said bowl to said conduit posteriorto said throttle valve, and fuel control means comprising an air bleedduct extending from said fuel passage to a port in the wall of saidconduit immediately anterior to said throttle valve when closed and abowl pressure control duct extending from the upper part of said bowland having branches termiof said valve.

15. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage extending from said bowlto said conduit posterior to said throttle valve, and fuel control meanscomprising an air bleed duct extending from said fuel passage to a portin the wall of said conduit immediately anterior to said throttle valvewhen closed and a bowl pressure control duct extending from the upperpart of said bowl and having branches terminating in said conduitthrough ports located, respectively, anterior and immediately posteriorto said throttle valve.

16. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, 2. main fuel passage extending from said bowlto said conduit posterior to said throttle valve, and fuel control meanscomprising an air bleed duct extending from said fuel passage to saidconduit immediately adjacent to the edge of said valve when closed and abowl pressure control duct leading from the upper part of said bowl to apair of ports in the wall of said conduit, respectively, immediatelyposterior to said throttle valve when closed and at a substantiallygreater distance posterior to said valve.

17. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage extending from said bowlto said conduit posterior to said throttle valve, and fuel control meanscomprising an air bleed duct extending from said fuel passage to a pairof ports in the wall of said conduit, respectively, immediately anteriorto said valve and at a greater distance anterior thereto and a bowlpressure control duct leading from the upper part of said bowl to saidconduit both anterior and posterior to said valve.

18. In a charge forming device for internal combustion engines, wallsforming an intake conduit, said intake conduit having an air inlet, amixing chamber, and a discharge outlet, a fuel bowl for said chargeforming device, means comprising a fuel supply conduit for maintainingthe fuel level in said supply chamber, a main fuel passage leading froma point below the fuel level in said fuel bowl and having an outlet inthe intake conduit, a throttle valve at a position in said intakeconduit anterior to said fuel passage outlet, an air passage leadingfrom a point in said intake passage anterior to the closed position ofsaid throttle to said fuel passage outlet, said throttle being of thebutterfly type and being so arranged and positioned with respect to theair passage that the portion of the periphery of the valve nearest theopening of the air passage moves toward the air inlet of the intakeconduit during the opening movement of the throttle, and in suchproximity to the air passage opening as to permit suction posterior tothe throttle to affect and reduce the pressure at the said air passageopening, and a second air passage leading from a point in said airpassage anterior to the closed position of said throttle to said fuelpassage outlet, said second air passage having an inlet in suchproximity to said throttle valve when it is moved to fully open positionas to cause the pressure at the said inlet to be reduced thereby.

19. In a charge forming device for internal combustion engines, wallsforming an intake conduit, said intake conduit having an air inlet, amixing chamber, and a discharge outlet, a fuel bowl for said chargeforming device, means comprising a fuel supply conduit for maintainingthe fuel level in said bowl, a main fuel passage leading from a pointbelow the fuel level in said fuel bowl and having an outlet in theintake conduit, a throttle valve at a position in said intake conduitanterior to said fuel passage outlet, an air passage leading from aninlet at a point in said intake conduit slightly anterior to the closedposition of said throttle to an outlet at said fuel passage, said airpassage inlet being traversed by said throttle as it moves toward openposition, and an air passage leading from a point in the intake conduitposterior to the throttle to a point above the fuel level in the fuelbowl, said air passage having its inlet located in position to be sweptduring the opening movement of the throttle so as to expose it tosuction posterior to the throttle thereby.

20. In a charge forming device for internal combustion engines, wallsforming an intake conduit, said intake conduit'having an air inlet, amixing chamber, and a discharge outlet, a fuel bowl for said chargeforming device, means comprising a fuel supply conduit for maintainingthe fuel level in said bowl, a main fuel passage leading from a pointbelow the fuel level in Said fuel bowl and having an outlet in theintake conduit, a throttle valve at a position in said intake conduitanterior to said fuel passage outlet, an air passage leading from apoint in said intake passage anterior to the closed position of saidthrottle to said fuel passage outlet, said throttle being of thebutterfly type and being so arranged and positioned with respect to theair passage that the portion of the periphery of the valve nearest theopening of the air passage moves toward the air inlet of the intakeconduit during the opening movement of the throttle, and in suchproximity to the air passage opening as to permit suction posterior tothe throttle to affect and reduce the pressure at the said air passageopening, and an air passage leading from a point in the intake conduitposterior to the throttle to a point above the fuel level in the fuelbowl.

21. In a charge forming device for internal combustion engines, wallsforming an intake conduit, said intake conduit having an air inlet, amixing chamber, and a discharge outlet, a fuel bowl for said chargeforming device, means comprising a fuel supply conduit for maintainingthe fuel level in said bowl, a main fuel pas- Sage leading from a pointbelow the fuel level in said fuel bowl and having an outlet in theintake conduit, a throttle valve at a position in said intake conduitanterior to said fuel passage outlet, an air passage leading from apoint in said intake conduit anterior to the closed position of saidthrottle to said fuel passage outlet, said throttle being of thebutterfly type and being so arranged and positioned with respect to theair passage that the portion of the periphery of the valve nearest theopening of the air passage moves toward the air inlet of the intakeconduit during the opening movement of the throttle, and in suchproximity to the air passage opening as to permit suction posterior tothe throttle to affect and reduce the pressure at the said air passageopening, and a second air passage leading from a point in said airpassage anterior to the closed position of said throttle to said fuelpassage outlet, said second air passage having an inlet in suchproximity to said throttle valve when it is moved to fully open positionas to cause the pressure at the said inlet to be reduced thereby, and anair passage leading from a point in the intake conduit posterior to thethrottle to a point above the fuel level in the fuel bowl.

22. In a charge forming device for internal combustion engines, wallsforming an intake conduit, said intake conduit having an air inlet, amixing chamber, and a discharge outlet, a fuel bowl for said chargeforming device, means comprising a fuel supply conduit for maintainingthe fuel level in said bowl, a main fuel passage leading from a pointbelow the fuel level in said fuel bowl and having an outlet in theintake conduit, a throttle valve at a position in said intake conduitanterior to said fuel passage outlet, an air passage leading from apoint in said intake conduit anterior to the closed position of saidthrottle to said fuel passage outlet, said throttle being of thebutterfly type and being so arranged and positioned with respect to theair passage that the portion of the periphery of the valve nearest theopening of the air passage moves toward the air inlet of the intakeconduit during the opening movement of the throttle, and in suchproximity to the air passage opening as to permit suction posterior tothe throttle to affect and reduce the pressure at the said air passageopening, and a branched passage having a connection to said intakeconduit at a point posterior to the throttle, another connection to saidintake conduit anterior to the throttle, and a third connection to thefuel bowl at a point above the fuel level therein.

23. In a charge forming device for internal combustion engines, wallsforming an intake conduit, said intake conduit having an air inlet, amixing chamber, and a discharge outlet, a fuel bowl for said chargeforming device, means comprising a fuel supply conduit for maintainingthe fuel level in said bowl, a main fuel passage leading from a pointbelow the fuel level in said fuel bowl and having an outlet in theintake conduit, a throttle valve at a position in said intake conduitanterior to said fuel passage outlet, an air passage leading from apoint in said intake conduit anterior to the closed position of saidthrottle to said fuel passage outlet, said throttle being of thebutterfly type and being so arranged and positioned with respect to theair passage that the portion of the periphery of the valve nearest theopening of the air passage moves toward the air inlet of the intakeconduit during the opening movement of the throttle, and in suchproximity to the air passage opening as to permit suction posterior tothe throttle to affect and reduce the pressure at the said air passageopening, and a second air passage leading from a point in said airpassage anterior to the closed position of said throttle to said fuelpassage outlet, said second air passage having an inlet in suchproximity to said throttle valve when it is moved to fully open positionas'to cause the pressure at the said inlet to be reduced thereby, and abranched passage having a connection to said intake conduit at a pointposterior to the throttle, another connection to said intake conduitanterior to the throttle, and a third connection to the fuel bowl at apoint above the fuel level therein.

24. An anterior throttle carburetor comprising a mixing conduit, aventuri in said mixing conduit, a constant level fuel bowl, a main fuelpassage leading from a point below the fuel level in said bowl anddischarging into said venturi, a throttle valve anterior to thedischarge outlet of said fuel passage, a suction passage leading from apoint in said mixing conduit posterior to said throttle to a point insaid constant level bowl above the fuel level, said suction passagehaving a branch leading to a point in the mixing conduit anterior to thethrottle.

25. An anterior throttle carburetor comprising a mixing conduit, aventuri in said mixing conduit, a constant level fuel bowl, a main fuelpassage leading from a point below the fuel level in said bowl anddischarging into said venturi, a throttle valve anterior to thedischarge outlet of said fuel passage, a suction passage leading from apoint in said mixing conduit posterior to said throttle to a point insaid constant level bowl above the fuel level, said suction passagehaving a branch leading to a point in the mixing conduit anterior to thethrottle, and a branched air bleed passage connected to said-fuelpassage i2 and having one of its branches so positioned as to be sweptby the edge of the throttle duringits opening movement.

26. An anterior throttle carburetor comprising a mixing conduit, aventuri in said mixing conduit, a constant level fuel bowl, a main fuelpassage leading from a point below the fuel level in said bowl anddischarging into said venturi, a throttle valve anterior to thedischarge outlet of said fuel passage, a suction passage leading from apoint in said mixing conduit posterior to said throttle to a point insaid constant level bowl above the fuel level, said suction passagehaving a branch leading to a point in the mixing conduit anterior to thethrottle, and an air bleedpassage connected to the fuel passage andhaving an inlet opening which is positioned anterior to the throttlewhen it is in closed position and is swept by the edge of the throttleas it moves toward open position.

2'7. In a carburetor, walls forming a mixing conduit, said mixingconduit having an air inlet, a mixing chamber, and a mixture outlet, abutterfly type throttle between said mixing chamher and said air inlet,a constant level fuel bowl a main fuel passage connected to saidconstant level bowl and discharging into said mixing conduit at a pointposterior to said throttle, an air bleed passage having an inlet openingin said mixing conduit anterior to said throttle when it is in closedposition, said opening being substantially spaced from the axis of saidvalve and located adjacent the edge which moves toward the inlet duringits opening movement, and means controlled by the throttle for reducingthe effect of said air bleed when the throttle approaches fully openposition.

28. In a carburetor, walls forming a mixing conduit, said mixing conduithaving an air inlet, a mixing chamber, and a mixture outlet, a butterflytype throttle between said mixing chamber and said air inlet, a constantlevel fuel bowl, a main fuel passage connected to said constant levelbowl and discharging into said mixing conduit at a point posterior tosaid throttle, an air bleed passage having an inlet opening in saidmixing conduit anterior to said throttle when it is in closed position,said opening being substantially spaced from the axis of said valve andlocated adjacent the edge which moves toward the inlet during itsopening movement, and means controlled by the throttle for reducing theeffect of said air bleed when the throttle approaches fully openposition, said means comprising a branch passage having an inlet in saidmixing conduit at a point anterior to the axis of said throttle, andhaving an extension which is approached by a part of the throttle as itmoves toward open position.

29. In a carburetor, a mixture conduit, a throttle valve therein, aconstant level fuel bowl, a main fuel passage connecting said bowl andsaid conduit posterior to said throttle valve, a bowl pressure controlduct extending from the upper part of said bowl to said mixture conduitfor controlling the fuel discharged from said passage, a connectionbetween said conduit and a zone of atmospheric pressure, valve meanscontroling said duct and said connection and actuable to open saidconduit to said zone during starting and warm-up-for increasing thepressure in the fuel discharge from said bowl into said conduit, saidstarting valve including portions for-reducing the effective-size of theconnection between said bowl pressure control duct and said conduit,while increasing the effective size of the connection between saidconduit and said zone of atmospheric pressure.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Name Date Wirth May 21, 1940 Fish Apr. 1, 1941 Messinger Apr. 22,1941 Dodson Apr. 22, 1941 Abramson May 27, 1941 Mock Feb. 24, 1942Boller June 20, 1950 FOREIGN PATENTS Country Date Great Britain Jan. 4,1934

